The invention relates generally to guide catheters, and more particularly to steerable, telescoping guide catheters used to locate and cannulate the coronary sinus of a patient""s heart.
Guiding catheters are instruments that allow a physician to access and cannulate vessels in a patient""s heart for conducting various medical procedures, including venography and implanting of cardiac pacing devices. Cannulating heart vessels requires navigating a small diameter, flexible guide through the tortuous vasculature into a heart chamber, and then into a destination heart vessel. Once the destination heart vessel is reached, the catheter acts as a conduit for insertion of payloads into the vessel.
A commonly accessed destination vessel for cardiac pacing lead insertion is the coronary sinus. A pre-shaped guiding catheter is typically used to blindly locate the coronary sinus ostium. This endeavor, however, is complicated by the fact that the location of the coronary sinus ostium may vary appreciably from one patient to another, especially among patients with diseased hearts. Oftentimes, the clinician is entirely unable to locate the coronary sinus ostium using the guiding catheter, and must resort to finding the ostium by xe2x80x9cmappingxe2x80x9d (interpreting localized bipolar waveforms) using an electrophysiological (EP) catheter and an ECG monitor. After the ostium is located, the guiding catheter is typically used to inject radiographic contrast media into the coronary sinus to highlight the associated venous system, and then a pacing lead is installed within one of the coronary branches.
Complicating this scenario is the dynamic structural deformation of the heart chambers that occurs from normal cardiac activity during the procedure. This further increases the difficulty of guiding a catheter to its destination. Presently, a considerable amount of time is often spent by the physician when manipulating such catheters within cardiac structures, such as the right atrium, simply trying to locate an anatomical feature of interest, such as the coronary sinus ostium.
Guiding catheter systems are typically configured with a profile that is optimized for the intended method of access. In the case of accessing the coronary sinus via the right atrium, a catheter with a distal contour including a relatively sharp bend will point the catheter towards the likely location of the coronary sinus once the right atrium is reached. The contours of pre-shaped guiding catheters are generally fixed, and this is typically achieved in production by constraining the distal end within a shaping fixture while warming them until they assume the intended shape (i.e., by xe2x80x9cheat settingxe2x80x9d their polymer shaft).
Guiding catheters are sometimes introduced over a pre-shaped guide wire that is inserted into the desired location first. The guide wire is typically small and maneuverable, and can be pre-shaped for the desired venous path. However, utilizing a guide wire prior to introducing the guide catheter is more time consuming as two operations are required. Shortening the time required to cannulate the desired vessels is desirable as it reduces the total procedure time and reduces trauma to the patient.
There is a need for an improved guide catheter having enhanced maneuvering capabilities for accessing blood vessels of interest and for cannulating those vessels. There exists a further need for a guiding catheter that accounts for anatomical variation and defects with the destination structures. The present invention fulfills these and other needs, and addresses other deficiencies of prior art implementations and techniques.
The present invention is directed to a guide catheter employing a telescoping inner guide and a deflectable outer guide. According to one embodiment of the present invention, the catheter includes an outer guide having a distal end, a proximal end, and a predetermined deflection location proximate the distal end. An inner guide section having an inner guide lumen and a pre-formed distal end is movably disposed within the outer guide. The inner guide section is displaceable beyond the distal end of the outer guide. An actuator mechanism located at the proximal end of the catheter changes a bend angle at the predetermined deflection location of the outer guide. The proximal end of the inner guide is accessible at the proximal end of the catheter allowing adjustable axial displacement of the pre-formed distal end of the inner guide relative to the outer guide.
In one configuration of the catheter, the inner guide can be axially displaced beyond the distal end of the outer guide within a range of 0 to about 20 centimeters. For example, at least 2 centimeters of the inner guide can be axially displaced beyond the distal end of the outer guide.
The pre-formed distal end of the inner guide may be configured to be deformable, such that the inner guide is retractable within the distal end of the outer guide. In one configuration, the inner guide is substantially more flexible than the outer guide, such that the distal end of the inner guide assumes the shape of the outer guide when the inner guide is retracted.
The bend angle at the predetermined deflection location of the outer guide can be defined relative to a longitudinal axis of the outer guide proximal to the predetermined deflection location. In one configuration, the bend angle can be adjustable from a minimum of about 0 degrees to a maximum of about 150 degrees.
A bend radius of the predetermined deflection location can be defined relative to a centerline of the predetermined deflection location. The bend radius is greater than about six times an outer diameter of the outer guide.
The inner guide is arranged such that axial forces exerted on the proximal end of the inner guide can extend and retract the pre-formed distal end of the inner guide relative to the distal end of the outer guide.
In one configuration, the catheter further includes at least one steering tendon connected to the inner guide proximate to the pre-formed distal end. The proximal actuator mechanism can produce a tensile force acting on the steering tendon(s). The tensile force acting on the steering tendon(s) imparts a change in the bend angle at the predetermined deflection location of the outer guide.
In another configuration, the catheter further includes at least one steering tendon connected to the outer guide proximate to the distal end. The actuator mechanism produces a tensile force acting on the steering tendon(s). The tensile force acting on the steering tendon(s) imparts a change in the bend angle at the predetermined deflection location of the outer guide.
The catheter may be configured such that an axial rotational force imparted on the proximal end of the outer guide rotates the pre-formed distal end of the inner guide. In one configuration of the invention, the catheter further includes a seal between the inner guide and the outer guide. The seal is typically located at the proximal end of the catheter.
According to a further embodiment of the present invention, the catheter further includes an occlusion balloon affixed to the distal end of the outer guide.
In one configuration, for example, the catheter further includes at least one electrode located proximate the pre-formed distal end of the inner guide. One or more electrical conductors can be coupled to the electrode(s) and extend through at least one of the inner and outer guide lumens to a proximal section of the catheter.
According to a further embodiment of the present invention, the catheter includes a plurality of band electrodes disposed at the distal end of at least one of the inner and outer guides. One or more electrical conductors can be coupled to the band electrode(s) and extend through at least one of the inner and outer guide lumens to a proximal section of the catheter.
According to another embodiment of the present invention, a method of inserting a payload into a coronary sinus of a patient""s heart involves providing a catheter having an outer guide, an inner guide and an actuator mechanism. The outer guide includes an outer guide lumen, a distal end, a proximal end, and a predetermined deflection location proximate the distal end. The inner includes an inner guide lumen, a pre-formed distal end, and a proximal end. The inner guide is movable within the outer guide lumen and displaceable beyond the distal end of the outer guide. The actuator mechanism is located at a proximal end of the catheter. The actuator mechanism changes a bend angle at the predetermined deflection location of the outer guide. The proximal end of the inner guide is accessible at the proximal end of the catheter, allowing adjustable axial displacement of the pre-formed distal end of the inner guide relative to the distal end of the outer guide.
The method further involves inserting the distal end of the catheter through a patient""s right atrium via an access vessel. The inner guide is distally displaced beyond the distal tip of the outer guide and the bend angle is changed at the predetermined deflection location via the actuator mechanism to direct the pre-formed distal end of the inner guide for finding and cannulating the patient""s coronary sinus. The outer guide is distally advanced over the inner guide to seat the outer guide in the patient""s coronary sinus. The inner guide is proximally retracted to remove the inner guide from the catheter. The payload is advanced through the proximal end of the outer guide such that the payload is inserted into the patient""s coronary sinus. In one aspect of the method, the payload includes a cardiac pacing lead.
According to yet another embodiment of the present invention, a method of inserting a payload into a coronary sinus of a patient""s heart involves inserting the distal end of the catheter through a patient""s right atrium via an access vessel. The inner guide is distally displaced beyond the distal tip of the outer guide and the bend angle is changed at the predetermined deflection location via the actuator mechanism to direct the pre-formed distal end of the inner guide for finding and cannulating the patient""s coronary sinus. The payload is advanced through the proximal end of the inner guide such that the payload is inserted into the patient""s coronary sinus. In one aspect of the method, the payload includes a cardiac pacing lead.
The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. Advantages and attainments, together with a more complete understanding of the invention, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.